The majority of junior golfers, most adult women and even a percentage of adult men, can hyperextend, or “lock out”, their lead elbow (e.g., left arm if swinging right handed). This often results from increased joint mobility. When a golfer is told to ‘keep lead arm straight,’ they have the ability to hyperextend their lead elbow, and as a result, lock out their lead shoulder. This hyperextended and locked out lead arm at address position then follows an almost identical swing path that is almost unfixable until the lead arm/shoulder is “unlocked” and free to move. This hyperextension prevents a good rotation of the arms and core (chest) in the backswing. The lead shoulder is literally locked in a position that prevents extension and rotation of the arm. When a player “locks out,” the lead arm's humerus bone rotates up and into the shoulder and therefore limits the lead shoulder's mobility for the duration of the swing. Most students “lock out” at the address or beginning, of the swing, while others “lock out” in the downswing just prior to impact. Once “locked” at address, several consistent swing-error moves are made to get the club to “parallel” (Uneven hips, “shut clubface”, straight trail leg . . . just to name a few). When “locked out” on the downswing, the lead shoulder/lead arm is prohibited, must lift/rise and compress against the clavicle/chest and shoulder blade as the lead arm is prevented from swinging down the target line, so the club is swung “left” of the target line. Poor, inconsistent shots are hit. The most detrimental aspect of this hyperextension is pain in the shoulder, neck, back and/or wrist. In some cases, pain becomes so chronic that extreme measures must be taken, such as administering nerve block to the affected area or even surgery.
A 2016 Study reports that Millennial men have lost 19 lbs. of grip pressure and Millennial girls have lost 11 lbs. compared to the same genders 30 years ago. https://www.washingtonpost.com/news/wonk/wp/2016/08/15/todays-men-are-nowhere-near-as-strong-as-their-dads-were-researchers-say/?utm_term=.3298977c2215 and http://www.jhandtherapy.org/article/S0894-1130(15)00212-4/fulltext
With a propensity for a weaker grip and extreme flexibility, the “lock out” elbow phenomenon is also present in other sports like softball, baseball, archery, etc. Accordingly, the present invention can assist players of other sports as well, and can also be adapted to prevent hyperextension of other the joints of other limbs, such as knees.